Seal for floating roof tanks



F. L.. GOLDSBY---ET AL SEAL FOR FLOTING ROOF 'TANKSv Filed Jan. 5, 1946 m @www Z475 ,bww w i Patented Mar. 22, 1949 UNITED STATES PATENT OFFICE' Fred L. Goxasby and cunard M. on, chicago, m., asslgnors to Chicago Bridge & Iron Company, a corporation of Illinois Application January 5, 1946, Serial No. 639,225 s claims. (ci. 22o-2s) This invention relates to a floating roof tank wherein the roof floats on top of the stored liquid, yand relates particularly to a seal for sealing the area between the edge of the roof and the shell of the tank.

In floating roof tanks there is sometimes provided a. shoe to rest against the shell of the tank in sealing relationship therewith and a flexible seal extending .from the shoe to the floating roof.

The roof rises and falls as the stored liquid within the tank is increased and decreased. There are usually provided supports on the bottom of the tank upon which the roof rests when the liquid level has been withdrawn below a given point. It has been found that when almost all liquid has been withdrawn the bottom of the sealing shoe is above the liquid level and the mixture of air yof the roof, and buoyant means immersed inthe stored liquid for Vpushing the shoe upwardly and outwardly against the shell.

The invention will be described as related to the embodiment shown in the accompanying drawings. Of the drawings, Fig. 1 is a fragmentary plan view of a oating roof tank embodying the invention with portions broken away for clarity of illustration; Fig. 2 is a vertical section taken along line 272er Fig. 1l showingthe roof floating on top of the stored liquid; and Fig. 3 is a view similar to Fig. 2 showing the roof resting on supports at the bottom of the tank.

The oating roof tank shown in the accompanying drawings comprises a shell l0, a bottom Il, a iioating roof I2 normally floating on the stored liquid I3 within the tank, a shoe I4 held against the shell l0, and a exible sealing mem-1 ber I5 extending between the top of the shoe It and the top surface of the floating roof I2.

The shoe |'4 is held against the shell III by means of a plurality of spaced support arms I6 hingedly attached to the shoe near the bottom thereof, and extending upwardly to near the top of the vertical edge of the oating roof |2j. The roof end of each support arm I6 is held in a slotted retainer I'I with the slot held away from the vertical edge of the roof and with the upper end of arm I 6 with- 2 in the slot. This upper end is held within the slot by means of a pin I8 extending from either side of the support arm I6 within the slot I9.

Near the bottom of each support arm I0 there is located a buoyant means comprising a downwardly extending arm 20 having a float 2| on the bottom end immersed in the stored liquid I3 with the bottom of each float being about even with the bottom of the shoe I4. The arm 20 is preferably rigidly fastened to the support arm I6 as by the plate 29 and rivets 30. All arms 2li may be connectedby an annular ring, if desired, to give greater rigidity, in which case the connections of arms il!)` to support arms I6 would be hinged.

On the bottom I`I of the tank there is located support means comprising a plurality of posts 22. These posts are to hold the oating roof above the bottom of the tank when the liquid is being withdrawn from the tank. The float 2| is preferably held immersed in the liquid I3 at a depth less than the height of the posts 22.

With the construction described above the Viioats 2| serve normally-to pushthe shoe I4 upwardly and outwardly against the shell III. When the roof is floating on top of the liquid each support arm IS will be held ywith its roof ,end at the top of its slotted retainer, Il. When the liquid is withdrawn from the tank the roof I2 come to rest on top of the posts 22. As the withdrawal of the liquid iscontinued the shoe, floats and support means go down with the liquid level. The bottom of the shoe is kept immersed in the liquid until substantially all liquid has been withdrawn. When the last portion is withdrawn the oats will be resting on the bottom of the tank.

The floats 2 must havesuiient buoyancy to support the weight of the shoe and other portions of the seal plus a small amount of friction. The shoe is preferably made in sections with each pair of adjacent sections joined to each other. The depth at which the floats 2| are immersed in the liquid I 3 depends upon the buoyancy o! the floats, the weight to be supported, the specific gravity of the liquid I3, and the friction of the shoe I4 against the shell lil. This depth may be so regulated that the oats will be resting on the bottom of the tank when the roof ends of the support arms i6 are substantially at the bottom of the slots I9. This construction, however, is not absolutely necessary. The bottom of the shoe I4 should be substantially even with, or just above, the bottom roof I2should`have a length greater than the shortest distance between its points of attachment to the shoe and the roof when the support is in its lowest position. The sealing member il, which may be of fabric impregnated with a ilexible impervious material. may be fastened to the top oitheshoebymeansotbolts 23 andtothe top edge of the root l2 by hooks 24 holding wedges 25 pressing against-a circular rod 29 in contact with the edge of the sealing member Il.

If desired. a secondary seal may be provided between the top of the shoe il and the shell I6 in order to provide a tighter seal. The secondary seal shown comprises a series of spaced brackets |26 mounted on the top edge of the shoe Il by bolts 21 with the brackets carrying a loop 28 ci ilexible sealing material in contact with the shell I0. A length oi flexible sealing material |29 extends between the loop- 28 and the top of the -shoe Il, and has its bottom edge held by the bolts 21.

Having described our invention as related to the embodiment shown in the accompanying drawings it is our intention that the invention be not limited by any of the details of descrip'- tion, but rather be construed broadly within its spirit and scope as set out in theaccompanying claims.

We claim:

1. In a oating roof tank comprising a shell and a floating roof therein normally floating on top of the stored liquid within the shell, a seal comprising a shoe held against the shell, a support arm hingedly attached nearthe bottom of the shoe and extending upwardly to the vertical edge of the roof. said roof end of the support arm being permissibly movable in a vertical direction along the vertical edge of the roof, and buoyant means attached to the support arm yarid immersed in the stored liquid for pushing the support arm and shoe upwardly.

2. The seal of claim 1 wherein the buoyant means is rigidly attached to the support arm near the shoe.

3. The seal of claim l wherein the buoyant means holds the shoe at the top 'of said path when the roof is floating on top of the stored liquid.

4. In a oating roof tank comprising ashell, a iioating roof therein normally iloating on top of the stored liquid within the shell, and support means on the bottom of the tank for supporting the roof above the bottom when the liquid level is beneath the top of the support means, a seal comprising 'a shoe held against the shell, a support arm hingedly attached to the shoe near the bottom of the shoe and extending upwardly'to the vertical' edge of the roo'i', means the buoyant meansissubstantially evvenwiththey bottom of the shoe.

6. The seal of claim 4 whereinthe buoyant means is rigidly attached to the support arm near the shoe. y

'1.Thesealof claim4wherein theholding means comprises a slotted retainer mounted on the vertical edge of the iloating root with the roof end oi' the support arm movably held in said slot.

8. In a floating roof tank comprising a shell, a floating root therein normally noating on top of the stored liquid within the shell, and support means on the bottom oi' the tank for supporting the roof above the bottom when the liquid level is beneath the top of the support means, a seal comprising a shoe held against the shell. a support arm hingedly attached to the shoe near the bottom oi the shoe and extending upwardly to the vertical edge of the roof, a slotted retainer mounted on the vertical edge of the floating roof with the root end ot the support arm movably held in said slot. and'buoyant means rigidly attached to the support arm near the shoe and immersed in the liquid to a depth less than the height of the support means, the bottom of said shoe being substantially even with the bot- REFERENCES CITED The following references are of record in the le of this patents.

UNITED sursis Parma Name Date Wiggins Feb. 23. 1926 Haupt Nov. 12, 1929 Johnson.- May 1,3. 1930 Kimbell July 19, 1932 Horton Mar. 21, 1933 Welp Jan. 8, 1935 Matter Jan.29, 1935 Number 

